Comparators are used in a wide variety of circuits. All comparators and operational amplifiers have an input offset voltage that reduces the accuracy of the comparator and/or operational amplifier. This can be problematic, especially when the difference between the signals to be compared is expected to be small. In fact, when the difference between the input signals to be compared is on the order of the input offset voltage of the comparator, the signal-to-noise ratio at the output of the comparator may approach one or more, effectively drowning out the signal of interest.
In some cases, a compensation voltage may be applied to the comparator to help compensate for the input offset voltage of the comparator. This is relatively straight forward when the input offset voltage is a static quantity and known. However, the input offset voltage of a comparator can vary between individual units and can vary with operating parameters, such as operating temperature, operating voltage and/or time. This can make it difficult to provide a compensation voltage that can effectively cancel out the input offset voltage for all comparators over time and over all expected operating conditions. This is particularly true when the difference between the input signals to be compared is small. What would be desirable is a system and method for actively compensating for the input offset voltage of a comparator.